A young fisherman discovers the body of Morgane near the entrance to Douarnenez harbour. According to Celtic legend, this is the exact location of the sunken city of Ys.

A young fisherman discovers the body of Morgane near the entrance to Douarnenez harbour. According to Celtic legend, this is the exact location of the sunken city of Ys.

And, oddly, the young woman was at the carnival the previous day and is still dressed as Dahut, the princess who brought about the downfall of the ancient city. Morgane, known to be an unscrupulous seductress, could have been murdered by a former lover or a rival. Or her murder could be linked to her father, the owner of the local sardine cannery, who rules over the town as its mythical king once did. One thing is certain, the murder scene echoes that of Dahut, drowned for her vices.

Tristan and Marion Legay are police investigators and a couple in their private life. When they arrive in Douarnenez, they immediately bump into old friend Katell. It should be a happy reunion, but it soon brings up an unsettling past.